Traction belt

ABSTRACT

An endless traction belt for vehicles having at least two endless bands laterally spaced, the bands being transversely interconnected by grouser bars attached to the outer surface of the bands. The grouser bars are longitudinally spaced on the bands with the region laterally intermediate the bands adapted to be contacted by driving-sprocket teeth. Transverse lugs of elastomeric material are formed on the outer periphery of the bands to a greater height than the grouser bars and the lugs are disposed closely adjacent opposite sides of each grouser bar such that the grouser bars are recessed between and supported by the lugs to prevent shearing of the grouser attaching means.

United States Patent Hallaman 1 Sept. 26, 1972 TRACTION BELT I PrimaryExaminer-Richard J. Johnson 72 inventor: Allan n. Hallaman, 1156 Dietzand JSePh Janus Ave., Akron, Ohio 44301 [22] Filed: Aug. 19, 1970 [57]ABSTRACT [21] Appl. No.: 65,060 An endless traction belt for vehicleshaving at least [52] US. Cl ..305/38 [51] Int. Cl. ..B62d 55/24 [58]Field of Search ..305/35 EB, 38

[5 6 References Cited 1 UNITED STATES PATENTS 3,205,023 9/ 1 965 Nodwell..305/38 2,936,196 5/1960 Baudelot ..305/35 EB 2,461,150 2/1949 Flynn..;..305/35 EB 3,451,728 6/1969 Bruneau ..305/35 EB 2,025,999 12/1935 Myers..305/38 two endless bands laterally spaced, the bands beingtransversely interconnected by grouser bars attached to the outersurface of the bands. The grouser bars are longitudinally spaced on thebands with the region laterally intermediate the bands adapted to becontacted by driving-sprocket teeth. Transverse lugs of elastomericmaterial are formed on the outer periphery of the bands to a greaterheight than the grouser bars and the lugs are disposed closely adjacentopposite sides of each grouser bar such that the grouser bars arerecessed between and supported by the lugs to prevent shearing of thegrouser attaching means.

2 Claims, 3 Drawing Figures l/ct PATENTEDSEPZB I972 FIG. 2.

TRACTION BELT BACKGROUND OF THE INVENTION Elastomeric traction belts arecommonly used for propelling tracked vehicles designed for traversingsoft surfaces such as mud, sand, soft earth and snow. Such belts areparticularly suited for use on recreational vehicles of the type knownas snowmobiles. Snwmo biles are usually supported by a suspensionprovided with at least one driving track and a pair of steerable skiiswith the latter being mounted in front of the driving track. The drivingtrack may either be a single endless band with apertures fonned throughthe surface of the belt in longitudinally equally spaced arrangement forengaging driving sprocket teeth, or the traction belt may be formed bytransversely interconnecting a plurality of laterally spaced bands. Inthis latter type of traction belt, one popular technique of laterallyinterconnecting the spaced bands is that of providing transversely orlaterally extending bars on the outer periphery of each band with thebars extending to interconnect all of the bands. These bars are known asgrouser bars, and are usually shaped in transverse cross section so theouter edges thereof contact the surface traversed such that the vehicletrack tends to rest on the grouser bars.

Grouser bars are also provided in snowmobile traction belts to providelateral stiffness to the belt and further to provide a rigid portionintermediate the laterally spaced bands, which portion is adapted tocontact, in a driving manner, the surface of the sprocket teeth. Thus,as mentioned above, several endless tracks bands may be joined laterallyby grouser bars with the bars providing thesurface for engaging thesprocket teeth, making it unnecessary to form apertures through thesurface of the elastomeric belt. This particular type of beltconstruction has been found to be quite economical and has gained wideusage in the manufacture of snowmobiles.

However, the means of attaching the grouser bars to the elastomericbands have caused difficulties. Rivets are commonly used for attachmentof the grouser bars to the track as a manufacturing expedient or,altematively, the grouser bar is bonded directly to the surface of theband during vulcanization without using separate mechanical fasteners.In service, as the grouser bars contact and drive over the surface to betraversed, the driving forces of the track belt are transmitted to thebelt through the rivets attaching the grouser bars, and these forcestend to rotate the grouser bars with respect to the surface of theelastomeric belt and further to shear the grouser bar fastening means ina direction longitudinally of the belt. When the vehicle traversesintermittently hard and soft surfaces as, for example, soft snow thenhard pavement, or ice, the grouser bar attaching means is subjected tohigh impulse shocks as the vehicle encounters sudden changes in thesurface. Quite often rivet failure, or elastomeric band failure, isencountered and the grouser bars become detached from the track belt.

As mentioned above, grouser bars are provided to give additional lateralstiffness to the traction belt and for absorbing the driving loads ofthe sprocket. However, it has been found, curiously enough, that suchbars do not increase the tractive ability of the belt over hard surfacesas ice or hard packed snow. When the snowmobile encounters ice, forexample, the grouser bars will often provide even less traction than anelastomeric traction surface due to the tendency of the surfaces of thegrouser bars to ice skate. In particular, if the vehicle is turnedsuddenly the grouser bars will cause the vehicle to slide sideways andoften to spin out uncontrollably. Therefore, it has been desirable tofind a technique to permit utilizing the grouser bars for stiffness andsprocket teeth engagement, yet provide an attachment of the grouser barswhich would not be subject to premature failure and further provide forpreventing the loss of traction on hard surfaces by the skating of thegrouser bars.

SUMMARY OF THE INVENTION The present invention provides a solution tothe above-described problem by providing a traction belt having severalendless elastomeric track bands spaced laterally and interconnected bymetal grouser bars rigidly attached to the outer surface of each of thebands and extending transversely between the bands. Traction increasingportions in the form of transverse integral elastomeric lugs are formedon the outer surface of each of the traction belts and extend outwardlytherefrom a distance greater than the height of any of the grouser barssuch that the bars are recessed below the outer surface of the lugs.Thus, the elastomeric traction increasing portions or lugs contact thesurface being traversed by the belt before the grouser bars, therebypreventing the grouser bars from direct contact with the surface beingtraversed. The transverse traction lugs are formed closely adjacentopposite sides of each grouser bar so as to provide resilient supportfor resisting relative rotation about an axis transverse to the belt, orshear of the grouser fastening means in a direction longitudinally ofthe belt.

The present traction belt thus retains the grouser bar for providinglateral stiffness and resistance to sprocket tooth loads, yet portionsof the elastomeric belt absorb the driving loads on the grouser barthereby preventing detachment of the grouser bars from the belt duringsevere service.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a portion ofthe presently preferred form of the traction belt;

FIG. 2 is a side elevation view of the embodiment of the belt shown inFIG. 1;

FIG. 3 is an isometric view of a portion of one of the endless bands ofthe belt of FIG. 1 showing details of the grouser bar attachment andtraction lugs.

DETAILED DESCRIPTION Referring now to FIG. 1 and 3, the snowmobile traction belt 10 is comprised of a plurality of endless track bands 1 1 ofelastomeric material, preferably reinforced with tension cords C withthe bands disposed in laterally spaced parallel arrangement so as toorbit in parallel, equally spaced, paths. The endless bands 11 areinterconnected by a plurality of grouser bars 12 of rigid material,preferably metal, attached to the outer surface of each of the bands 11such that each of the bars 12 extends transversely the entire width ofthe traction belt 10. The bars 12 are longitudinally spaced equallyalong the surface of the bands 11 an amount determined by the desiredpitch of the driving sprocket (not shown) to be engaged on a snowmobile.In the presently preferred form of the invention, shown in FIG. 1, threeof the endless bands 1 1 are provided so as to permit driving by twoaxially spaced sprockets. The grouser bars are engaged on the sidesthereof by the sprockets along the portion of their length intermediatethe spaced bands 11. However, it will be understood that if desired,only two of the bands 11 may be used with the belt being engaged by asingle sprocket.

The grouser bars 12 are preferably attached mechanically to the trackbelt bands 11 by an convenient expedient sufficient to absorb thesprocket driving loads. In the present preferred form of the invention,rivets 13 are utilized with. each of the rivets penetrating thethickness of the band to attach the grousers to the bands 11. However,other fastening means may be used, for example bolts or, alternatively,directly bonding the metal grouser to the band by vulcanization.-Thepresently preferred grouser bar 12 is formed of sheet metal stamped to aU-shape, or cup shape, in transverse cross section with the open edgesextending outwardly from the surface of the traction belt. However, itwill be understood the grouser bars may also be made as solid barsformed to any convenient polygonal shape or, alternatively, by roundbars.

Referring now to FIG. 3, each of the endless bands 1 1 has a pluralityof traction increasing lugs 1 la formed on the outer surface thereofwith the lugs extending transversely of the bands 11. The lugs areformed integrally with the bands 11 and are disposed adjacent the edgesof each of the grouser bars in a manner so as to support the grouserbars longitudinally of the bands 11.

Preferably, as shown, the lugs on either side of a grouser bar have thesurfaces adjacent the latter in contact therewith and complementary inshape thereto.

Each of the lugs 11a extends outwardly from the surface of the band 11by a distance greater than the height of the grouser bar. In thepresently preferred practice of the invention, the transverse tractionlugs 11a extend outwardly from the surface of the belt generallyone-sixteenth of an inch further than the grouser bars; however, it willbe understood that the lugs 11a may extend a greater amount if sodesired. Preferably as illustrated in FIG. 3, the transverse lugs 11aextend the full lateral width of each of the bands 11. However, the lugs11a, if desired, may extend a lesser amount than the full width of theband 11 with the length of the lugs 11a being determined by therequirements for providing rotational support for the grouser bars 12about the fasteners 13.

A plurality of longitudinally extending lugs 11b is also provided on theouter surface of each of the endless bands 1 l in the preferred form ofthe invention. The longitudinally extending lugs 11b are disposedintermediate the axial edges of each of the bands 11 with each of thelugs 11b extending longitudinally so as to interconnect adjacenttransverse lugs 1 1a. The longitudinal lugs 1 lb are provided forincreasing the resistance of the traction belt 10 to lateral skiddingand thus provide for better directional tracking. Each of the longitudinal lugs 11b isintegral with and preferably extends from the surfaceof the traction belt to the same height as the transverse lugs 11a.However, if desired, the longitudinal lugs 11b may be recessed below theheight of the transverse lugs 11a. In the preferred practice of the 5invention illustrated in FIGS. 1 and 3, only one longitudinal lug 1 1bhas been provided for interconnecting adjacent transverse lugs 11a.However, it will be understood that more than one longitudinal lug 1 lbmay be provided intermediate any two adjacent transverse lugs 1 1a, ifdesired, to provide increased tracking ability or to provide desirableappearance to the pattern of the traction lugs 11a and 11b.

The present invention thus provides an endless elastomeric traction beltfor snowmobiles having grouser bars laterally interconnecting spacedtraction bands. Lug portions formed on the outer surface of each of thetraction bands adjacent the grouser bars extend to a greater height thanthe bars such that the grouser bars do not normally contact the surfacebeing traversed by the vehicle and movement of the grouser bars relativeto the surface of the belt is resisted by the lugs.

Modifications and adaptations of the invention may be made by thosehaving ordinary skill in the art and the invention is limited only bythe spirit and scope of the following claims.

I claim:

1. An endless traction belt of reinforced elastomer for sprocket-driventracked vehicles characterized in that the said belt has:

a. a plurality of endless flexible track bands disposed so as to orbitin axially spaced parallel arrangement;

b. a plurality of elongated grouser bars of rigid material mountedtransversely on the outer periphery of said bands in longitudinallyspaced parallel arrangement with each bar interconnecting transverselyall of saidbands and with the portions of each bar intermediate saidtrack bands being adapted to contact the teeth of at least one drivingsprocket;

c. a plurality of transverse lugs formed integrally on the outerperiphery of each of said bands and extending outwardly therefrom anamount greater than the height of said grouser bars with one of saidlugs disposed closely adjacent respectively opposite sides of each ofsaid grouser bars, the transverse lugs between each pair of grouser barsbeing spaced from each other in a direction longitudinally of said belt;and,

d. a plurality of longitudinal lugs extending outwardly from the outerperiphery of each of said bands with one of said longitudinal lugsdisposed longitudinally intermediate each two of said adjacent grouserbars and with each of said longitudinal lugs extending longitudinally ofsaid track band integral therewith and with the said transverse lugsadjacent each of said grouser bars, the transverse width of each of saidlongitudinal lugs being substantially less than the width of the band onwhich it is located.

2. The traction belt defined in claim 1, further characterized in thateach of said longitudinal lugs extends outwardly from the outerperiphery of said band 65 the same distance as said transverse lugportions.

1. An endless traction belt of reinforced elastomer for sprocket-driventracked vehicles characterized in that the said belt has: a. a pluralityof endless flexible track bands disposed so as to orbit in axiallyspaced parallel arrangement; b. a plurality of elongated grouser bars ofrigid material mounted transversely on the outer periphery of said bandsin longitudinally spaced parallel arrangement with each barinterconnecting transversely all of said bands and with the portions ofeach bar intermediate said track bands being adapted to contact theteeth of at least one driving sprocket; c. a plurality of transverselugs formed integrally on the outer periphery of each of said bands andextending outwardly therefrom an amount greater than the height of saidgrouser bars with one of said lugs disposed closely adjacentrespectively opposite sides of each of said grouser bars, the transverselugs between each pair of grouser bars being spaced from each other in adirection longitudinally of said belt; and, d. a plurality oflongitudinal lugs extending outwardly from the outer periphery of eachof said bands with one of said longitudinal lugs disposed longitudinallyintermediate each two of said adjacent grouser bars and with each ofsaid longitudinal lugs extending longitudinally of said track bandintegral therewith and with the said transverse lugs adjacent each ofsaid grouser bars, the transverse width of each of said longitudinallugs being substantially less than the width of the band on which it islocated.
 2. The traction belt defined in claim 1, further characterizedin that each of said longitudinal lugs extends outwardly from the outerperiphery of said band the same distance as said transverse lugportions.